Patent GB-735302-A (GB)
Title: Improvements in or relating to maleamic esters
IPC: C07C233/02
Filed: 1952-05-01
Abstract: The invention comprises maleamic esters of the formula <FORM:0735302/IV (b)/1> where R is alkyl, aralkyl, alkenyl, or a halogen-, sulphur-, or nitrogen-substituted derivative thereof, X and Y are hydrogen or halogen, Z is an organic group or a negative group non-reactive with an aliphatic alcohol, and n is 1-5, subject to the following limitations: (1) Z is organic when both X and Y are hydrogen; (2) when X and Y are different the position of the halogen atom is the same as that in the maleamic acid obtained by the reaction of a halomaleic anhydride with an aromatic amine; (3) N - (p - tolyl) - bromo - maleamic methyl ester is excluded.  These are made by esterification of the corresponding maleamic acids with ROH in the presence of an esterification catalyst.  In the examples the following are prepared by reacting the corresponding maleic anhydride with the appropriate arylamine and esterification of the product: methyl N-(o-phenylphenyl) - maleamate, methyl N - (p-phenylphenyl) - maleamate, methyl N - (p-acetylphenyl) - maleamate, N - (p - nitrophenyl)-chloromaleamate and butyl N-(2 : 5-dichlorophenyl)-chloromaleamate.  Esterification is effected by refluxing the acid with the alcohol in the presence of p-toluenesulphonic acid, or in the last case by conversion of the acid into the silver salt and reaction with butyl iodide.  Other acids that may be esterified are N-(o-tolyl)-chloromaleamic, N - (p - aminophenyl)-chloromaleamic, N - (p - phenylphenyl) - dibromomaleamic, N - (2 - nitro - 4 - hydroxyphenyl) - chloromaleamic and N - (p - bromophenyl) - dichloromaleamic. In general Z may be alkyl, aralkyl, alkenyl, aryl, aralkyl, chloro, bromo, mercapto, trichloromethylthio, hydroxy, alkoxy, aryloxy, amino, alkylamino, arylamino, nitro, nitroso or aminomethyl.  R is preferably an alkyl group not above octyl, e.g. methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl or pentyl.ALSO:Fungicidal compositions comprise essentially a maleamic ester of the formula <FORM:0735302/VI/1> and a major proportion of a surface contacting agent or a fungicidally inert adjuvant as a carrier therefor.  In the formula R is alkyl, aralkyl, alkenyl, or a halogen-, sulphur- or nitrogen-substituted derivative thereof, X and Y are hydrogen or halogen, Z is an organic group or a negative group non-reactive with an aliphatic alcohol, and n is 1-5, subject to the following limitations: (1) Z is organic when both X and Y are hydrogen; (2) when X and Y are different the position of the halogen atom is the same as that in the maleamic acid obtained by the reaction of a halomaleic anhydride with an aromatic amine; N-(p-tolyl)-bromomaleamic methyl ester is excluded.  The compounds may be applied in various ways, e.g. (a) in aqueous suspension with an anionic or non-ionic wetting agent; (b) in solution in an organic solvent, various hydrocarbons, ketones, chlorine compounds, esters, alcohols and glycol monoethers being mentioned; (c) with a solid diluent such as talc or clay. Particular compounds stated to be suitable are the methyl, ethyl, propyl, butyl and hexyl esters of N-(o-phenylphenyl)-maleamic acid, N - (p - nitrophenyl) - chloromaleamic acid and N - (p - phenylphenyl) - maleamic acid. Other suitable compounds are mentioned.